JPH11141630A - Auto tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the rattling of an arm due to the wear of bearings. SOLUTION: An arm 40 is mounted at the opening of a cup 22 to be rotationally movable around a pivot. A pulley 50 is rotatably mounted on the arm 40. A driving belt is suspended on the pulley 50. A torsional coil spring 80 energizes the arm 40 in a preset rotating direction. A damping band 70 is fixed to the arm 40. When the arm 40 is oscillated, the damping band 70 is slid with the cup 22 to allow the vibration of the driving belt transmitted to the arm 40 to be damped. A first bearing 62 and a second bearing 64 are mounted between the arm 40 and the pivot 30. Two bearings 62, 64 are provided to be reduced in wear, thus to prevent the rattling of the arm 40 to the pivot 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto tensioner used for a belt drive mechanism of an automobile engine, for example.

[0002]

2. Description of the Related Art An automatic tensioner is used for a transmission device that transmits driving force to a plurality of devices with a single belt, and prevents the belt from being loosened so that the driving force is transmitted to each device reliably. Such an auto-tensioner includes, for example, a cup fixed to a predetermined portion such as an engine block, an arm swingably supported by the cup, and a pulley rotatably attached to the arm. I have. The belt is suspended on the side surface of the pulley, and is urged in a tensioning direction. The biasing force for tensioning the belt is generated by a repulsive force of a torsion coil spring wound around a predetermined torsion force and disposed in the cup.

[0003] The arm is attached to a swing shaft integrally fixed to the cup. Since the load of the belt tension transmitted to the arm is imbalanced on the swing shaft, a bearing made of resin or the like is provided between the arm and the swing shaft, for example, in order to prevent early breakage. The burden is even.

[0004]

When the auto-tensioner is used under severe conditions, the bearing is worn and a gap is created between the arm and the swinging shaft. May lean against. The inclination of the arm causes a decrease in durability of the pulley bearing, a contact with an external device, and an abnormal noise of the belt.

In view of the foregoing, an object of the present invention is to provide an automatic tensioner that prevents the arm from tilting due to wear of a bearing.

[0006]

An auto-tensioner according to the present invention comprises a cup having a bearing formed in the center, an oscillating shaft fixed to the cup by being screwed into the bearing of the cup, and a cup. An arm rotatably mounted around the pivot axis in the opening of the first bearing section, wherein the arm is provided outside the outer peripheral surface of the first bearing section into which the pivot axis is inserted, and the cup bearing section. And a bearing portion.

In the automatic tensioner, preferably,
A bearing is provided between the cup bearing and the second bearing.

In the automatic tensioner, preferably,
A cup bearing is formed to protrude from the bottom surface of the cup toward the cup opening, and a second bearing is formed to protrude from the cup opening toward the cup bottom.

In the automatic tensioner, preferably,
The rocking shaft is fixed to the cup by screwing into the bearing. Preferably, a swing shaft is formed integrally with the cup.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an auto tensioner according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a belt system of an automobile engine using an auto-tensioner according to a first embodiment. The belt system includes a driving pulley 11 attached to an output shaft of an engine, driven pulleys 12, 13, and 14 for an air conditioner, a power steering device, and an alternator, idler pulleys 15, 16, and an auto tensioner (hereinafter, referred to as an auto tensioner). , Tensioner) 10. A single drive belt 17 between each pulley
Is suspended, and the drive belt 17 is driven clockwise.

The tensioner 10 has a fixing portion 20, which is fixed to the engine block. The tensioner 10 has an arm 40. This arm 40
Is rotatable around an axis (not shown) with respect to the fixed portion 20. A pulley 50 is attached to the arm 40, and the pulley 50 is rotatable with respect to the arm 40. The drive belt 17 is suspended around the outer peripheral surface of the pulley 50. The pulley 50 is urged counterclockwise from the position indicated by the solid line by a torsion coil spring (not shown) to move to the position indicated by the broken line, and tensions the drive belt 17.

The configuration of the auto-tensioner according to the first embodiment will be described with reference to FIGS. FIG. 2 is a sectional view showing the structure of the auto tensioner, and FIG. 3 is an exploded view showing parts of the auto tensioner.

The fixing part 20 has a cup 22. Two mounting holes 21 are provided on the outer periphery of the cup 22. A bolt (not shown) is inserted into the mounting hole 21, whereby the fixing portion 20 is fixed to the engine block. At the center of the bottom surface 22 a of the cup 22, a bolt engaging portion 24 that stands up into the cup 22 is formed. The screw portion 3 formed at the lower end of the pivot shaft 30
2 are screwed together, whereby the pivot shaft 30 is fixed to the fixing portion 20.

FIG. 4 is a plan view of the cup 22 as viewed from above. Three protrusions 201, 202, and 203 are formed on the bottom 22 a of the cup 22 to restrict the movement of the torsion coil spring 80 in the rotation direction. The straight portion 82 of the torsion coil spring 80 has two protrusions 201, 202.
The torsion coil spring 80 is fixed to the cup 22. Also, the torsion coil spring 80
Abuts on the protrusion 203 to restrict the movement in the radial direction.

Referring again to FIG. 2 and FIG. The arm 40 is made of a metal material, and is a lid 42 which is two disc members.
And the pulley mounting portion 43 are eccentrically overlapped.

The pulley mounting portion 43 has a pulley bearing 45 at the center.
It has. A pulley shaft 52 is screwed into the pulley bearing 45 via a pulley 50 and a dust shield 56, whereby the pulley 50 is attached to the arm 40. A ball bearing 52 is interposed between the pulley 50 and the pulley bearing 45, so that the pulley 50 is rotatable around a pulley shaft 54. The dust shield 56 prevents dust from entering the ball bearing 52 and the like.

At the approximate center of the lid 42 of the arm 40, a first
Is formed so as to protrude upward. A first bearing bushing 62 is fitted into the first bearing portion 44 from above. The first bearing bushing 62 has a flange at the upper end, and the outer diameter of the flange is substantially the same as the outer diameter of the first bearing bushing 62. The first bearing bushing 62 is in close contact with the inner peripheral surface of the first bearing portion 44 and is in close contact with the outer peripheral surface of the pivot shaft 30.

The cover 42 has a larger diameter than the first bearing 44 and includes a second bearing 46 projecting downward from substantially the center of the cover 42. The second bearing 46 communicates with the first bearing 44. A second bearing bushing 64 is fitted into the second bearing portion 46 from below. The second bearing bushing 64 has a flange portion formed at the lower end,
The outer diameter of the flange portion is substantially the same as the outer diameter of the second bearing bushing 64. As shown in FIG. 2, the second bearing bushing 64 is in close contact with the inner peripheral surface of the second bearing portion 46 in a state where the second bearing bushing 64 is attached to the second bearing portion 46.
And the inside of the second bearing 46 is sealed. The flange portion is in close contact with the lower end of the second bearing portion 46 to prevent dust from entering the second bearing 46.

The pivot shaft 30 fixed to the fixing portion 20 is inserted into the first bearing bushing 62 and the nut 3
4 regulates the vertical direction. In this manner, the lid 4
2 is rotatably attached to the opening of the cup 22.
That is, the arm 40 can rotate with respect to the fixed portion 20 around the pivot shaft 30 which is a swing shaft with a predetermined frictional resistance.

FIG. 5 is a view of the arm 40 as viewed from the cup side (the lower side in FIG. 3). The lid portion 42 has two pins 48 on the lower surface 42a side, and the two pins 48
a extends in the direction of the pivot axis 30 from FIG. This 2
The two pins 48 fit into the engagement holes 72 formed in the damping band 70, and thereby the damping band 70 is attached to the arm 40 (see FIG. 2). A fan-shaped locking portion 49 protruding toward the cup 22 is formed near the first bearing portion 44 on the lid lower surface 42 a of the arm 40. The torsion coil spring 80 is fixed to the arm 40 in the circumferential direction by locking the bending portion 86 to the sector locking portion 49.

The damping band 70, which is a friction member,
It is provided between the cup inner peripheral surface 22b of the fixing portion 20 and the arm 40, and is formed of an elastic member such as a nylon resin. The damping band 70 is provided to prevent the arm 40 from swinging excessively, and attenuates the swing of the arm 40 by a frictional force with the inner peripheral surface 22b, that is, a damping force.

Two cylindrical holes (hereinafter referred to as mounting holes) 72 of the damping band 70 are formed to protrude inward from the annular portion 71 on the flange portion 73 side. The diameter of the mounting hole 72 is substantially the same as the outer diameter of the pin 48 of the arm 40. By inserting the pins 48 into the mounting holes 72, the relative movement in the rotating direction and the radial direction of the damping band 70 with respect to the arm 40 is restricted.

When the damping band 70 is attached (see FIG. 2), the shoulder 73a of the flange portion 73 and the lower surface 42a of the lid of the arm 40 are substantially in close contact with each other, and the annular portion 71
Outer peripheral surface 71a and cup inner peripheral surface 22a are in close contact with each other. That is, the inside of the cup 22 is substantially sealed by the arm 40 and the damping band 70. The flange portion 73 of the damping band 70 is provided to prevent dust from entering the inside of the cup 22.

The ring spring 74 is made of a metal wire C
It is a shaped spring and is attached to the inner peripheral surface 71b of the damping band 70 in a state of being contracted in the radial direction. In the first embodiment, two sheets are attached in the axial direction. The plate width (radial dimension) of the ring spring 74 is gradually increased from the opening 76 side toward the mounting hole 72 side. The ring spring 74 is provided on the inner peripheral surface 71 of the damping band 70.
b, and is axially held between the ring spring receivers 75a and 75b and the mounting hole 72. The two ring springs 74 urge the damping band 70 toward the cup 22 with a substantially uniform and constant force. Thus, when the arm 40 swings, the damping band 70 and the cup 2
2, a damping force is generated by a frictional force on the surface in contact with the sliding member 2. This damping force is constant irrespective of the torsional force of the torsion coil spring 80. The biasing force of the ring spring 74 is appropriately set according to the required damping force.

The torsion coil spring 80 is formed by spirally winding a metal wire, and has a spiral portion 84 having a constant diameter, a straight portion 82 formed at one end of the spiral portion 84,
And a bent portion 86 formed on the other end side. The straight portion 82 is fixed to the cup bottom 22a (see FIG. 4), and the bent portion 86 is fixed to the lid lower surface 42a of the arm 40 (see FIG. 5). The torsion coil spring 80 is interposed in a compressed state between the cup 22 and the arm 40 in an appropriately twisted state, and in this state, in a direction to tension the drive belt 17 (see FIG. 1) suspended on the pulley 50. The arm 40 is urged.

When the drive belt 17 (see FIG. 1) is driven, the pulley 50 and the arm 40 swing around the pivot shaft 30 with the vibration of the drive belt 17. Swings together,
It slides on the inner peripheral surface 22a of the cup 22. As described above, the tensioner 10 of the first embodiment is provided with the damping mechanism including the damping band 70 and the ring spring 74.
2, a damping force is generated, and the vibration of the arm 40 and the pulley 50 is attenuated.

Conventionally, the load applied to the pivot shaft during belt driving is large, and under severe conditions, the bearing is worn, resulting in a gap between the arm and the bearing or between the bearing and the pivot shaft, and as a result, the arm is tilted. This causes abnormal noise and rattling. However, in the first embodiment, two bearings 44 and 46 are formed on the arm 40, and the bearings 44 and 46 are provided with bearing bushings 62 and 64, respectively. Therefore, the load applied to the pivot shaft 30 is reduced not only by the arm 40 but also by the outer side of the cup bearing 24, thereby reducing the wear of the bearing bushings 62 and 64. That is, the arm 40 and the pivot shaft 3
No gap is generated between the arm 40 and the arm 40, and the arm 40 does not tilt. Therefore, it is possible to prevent the durability of the ball bearing 52 from decreasing, the generation of abnormal noise of the drive belt 17, the contact with the external device, and the like.

FIGS. 6 to 9 show a second embodiment of the automatic tensioner of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 6 is a sectional view of the auto tensioner. FIG. 7 is a top view of the swing shaft along the line VII-VII, FIG. 8 is a top view of the E-shaped retaining ring,
FIG. 9 is a side view of the upper end of the swing shaft.

The swing shaft 132 is formed integrally with the cup 22. The swing shaft 132 has a cylindrical shape with a smaller diameter than the bearing 24, extends from the bearing 24 toward the pulley 50, and projects from the cup opening surface. This swing shaft 13
The arm 40 is attached to 2 via a bearing bushing 62. A flat washer 135 is in close contact with the flange upper surface 62a of the bearing bushing 62.
Urges the collar upper surface 62a of the bearing bushing 62 toward the cup 22 by the E-shaped retaining ring 136. As shown in FIG. 9, the head of the swing shaft 132 has a groove 1 over the circumferential direction.
34 are formed. As shown in FIG. 7, an E-shaped retaining ring 136 is fitted into the groove 134, whereby the arm 40 is axially fixed to the cup 22, that is, the fixing portion 20.

As shown in FIG. 8, an E-shaped retaining ring 136 is a ring spring having a partly open end, and has two ends 137, 1
The inner wall 139 opposite to the opening 38 is formed to have a large radial thickness. Inner peripheral surface 137 of this thick protrusion
a, 138a and 139a are grooves 134 of the swing shaft 132.
Adhere to As a result, the E-shaped retaining ring 136 is
32 are locked in the radial and axial directions.

Also in the second embodiment, the two bearings 4
4, 46 and the bearing bushings 62, 64 are provided, respectively, so that the load on the pivot shaft 30 is reduced. That is, wear of the bearing bushings 62 and 64 is reduced, and the arm 4
There is no gap between the zero and the pivot shaft 30 due to wear, and no tilt of the arm 40 occurs. Therefore, it is possible to prevent the durability of the ball bearing 52 from decreasing, the generation of abnormal noise of the drive belt 17, the contact with the external device, and the like.

[0033]

According to the present invention, it is possible to obtain an auto-tensioner for preventing the arm from tilting due to wear of the bearing.

[Brief description of the drawings]

FIG. 1 is a front view showing an auto tensioner of a first embodiment together with a belt system of an automobile engine.

FIG. 2 is a cross-sectional view of the auto tensioner shown in FIG.

FIG. 3 is an exploded sectional view showing parts of the auto tensioner shown in FIG. 2;

FIG. 4 is a plan view showing a fixing portion of the auto tensioner shown in FIG. 2 together with a torsion coil spring.

FIG. 5 is a plan view of the arm of the auto tensioner shown in FIG. 2 as viewed from below.

FIG. 6 is a sectional view of an auto-tensioner according to a second embodiment.

7 is a top view of the swing shaft shown in FIG. 6 taken along line VII-VII.

FIG. 8 is a top view of the E-shaped retaining ring shown in FIG.

FIG. 9 is a side view of the swing shaft shown in FIG. 6;

[Explanation of symbols]

 Reference Signs List 10 Auto tensioner 17 Drive belt 22 Cup 30 Pivot shaft 40 Arm 50 Pulley 70 Damping band 80 Torsion coil spring

Claims (5)

[Claims] 1. A cup having a bearing portion formed at the center, a swing shaft integrally fixed to the bearing portion of the cup, and an arm rotatably attached to the cup opening around the swing axis. Wherein the arm includes a first bearing portion into which the swing shaft is inserted, and a second bearing portion provided outside the outer peripheral surface of the bearing portion of the cup. . 2. A bearing is provided between a bearing portion of the cup and the second bearing portion.
Auto tensioner as described in. 3. The bearing of the cup is formed to project from the cup bottom toward the cup opening, and the second bearing is formed to project from the cup opening toward the cup bottom. 2. The method according to claim 1, wherein
Auto tensioner as described in. 4. The auto-tensioner according to claim 1, wherein the swing shaft is fixed to the cup by screwing into the bearing. 5. The auto-tensioner according to claim 1, wherein the swing shaft is formed integrally with the cup.